Practical Skills Flashcards
Name the 7 SI units
Meters m
Seconds s
Kilograms kg
Kelvins k
Amps A
Mole Mol
Candela cd
Tera as a power of 10
10^12
Giga as a power of 10
10^9
Mega as a power of 10
10^6
Kilo as a power of 10
10^3
Centi as a power of 10
10^-2
Milli as a power of 10
10^-3
Micro as a power of 10
10^-6
Nano as a power of 10
10^-9
Pico as a power of 10
10^-12
Femto as a power of 10
10^-15
Independent variable
What you’re in charge of changing
Dependent variable
What you measure
Control variables
What you keep the same
1st step of experiment planning
Find an equation that answers the question
2nd step of experiment planning
Decide what needs to be measured
3rd step of experiment planning
Decide what equipment will be precise
4th step of experiment planning
Decide independent dependant and control variables
5th step of experiment planning
Draw a diagram to show how equipment should be set up
6th step of experiment planning
Test the largest and smallest values you can get from Independant variable
7th step of experiment planning
Write method
Experiment design steps summary
-Make hypothesis/prediction
-Decide what data to collect/how
-Find Independant dependant and control variables
-Select appropriate equipment
-Risk assessment
Hazard
Anything that can cause harm
Risk
How someone could be harmed by a hazard
Prevention
How to stop someone being harmed
What does a full rotation on a micrometer mean
A 1/2 mm line on main scale
What’s on the micrometer rotating scale
50 divisions each 0.01 mm
How to read micrometer
1)Look what line has just been uncovered on main scale
2)See what number rotating scale lines up with on main scale
3)Add main and rotating scale together
Advantage of micrometer
-They are all the same
-Can’t overtighten and squash due to ratchet
-More precise (0.01mm rotating scale)
Vernier calliper advantages
-Upper jaws to measure internal diameter
How to read vernier callipers
-Look for 0
-Vernier scale= zoomed version of 1mm.
1mm÷increments
-Look where line on main scale matches vernier scale
-Add this to main scale reading
Tables rules
-Units separated from quantity with /
-Independant variable on left
-Record all data and averages to the same DECIMAL places
-Calculated data should be rounded to lowest number of significant figures
Graph rules
-Fill grid
-Axis doesn’t need to start at 0
-Line/curve of best fit
-Don’t join dots
-Label axis
-Circle obvious anomalies
How to do error bars
Calculate mean value.
Calculate range
Divide range by 2 for absolute uncertainty
Absolute uncertainty above and below mean
Systematic error
Errors that affect all measurements by the same amount
Example of systematic error
A balance that reads already 0.4g and this is added to each measurement
How to reduce systematic errors
Reduce effects by calibrating equipment
Random error definition
An error that affects all measurements bt different amounts
Example of random error
Human reaction time with a stopwatch
How to reduce random error
Reduce effects by taking repeat readings so you can spot and remove anomalies
Take an average to smooth out results
Parallax error definition
-Type of random error
-Caused by eye, object measured and measuring device.
-Eliminate using set square or place object directly under measuring device
Calibration error
-Type of systematic error
-Caused when you don’t check equipment is reading 0 when it should be
-Check it reads 0 or measure something of known size
What is the uncertainty in a reading
+example of equipment
Where you look at equipment once to make judgement
Eg: thermometer, cylinder, geuger
±1/2 the smallest division
What is uncertainty in a measurement
+Example of equipment
Where you look at equipment twice to make a judgement.
Eg: Calliper, protracter, ruler
±1 the smallest division
Uncertainty in digital meters
+example of equipment
Eg: stopwatch, voltmeter
±1 the smallest division
Uncertainty in exam data
Assume ± in the last significant digit
How to calculate percentage uncertainty
(Absolute uncertainty÷reading) x100
How to calculate uncertainty when adding 2 measurements
Add absolute uncertainties
How to calculate uncertainty when subtracting 2 measurements
Add absulute uncertainties
How to calculate uncertainty when multiplying 2 digits
Add percentage uncertainties
How to calculate uncertainty when dividing 2 digits
Add percentage uncertainties
How to calculate uncertainty when you raise a value to a power
Multiply uncertainty by the power
If you measure thickness of a coin by finding thickness of stack of 10 and then dividing that by 10 what happens to % uncertainty?
Stays the same
How to calculate uncertainty from a range of results
Find range
Divide range by 2 for absolute
Find mean
(Absolute÷mean) x100
Precise result
Small spread in the data from the mean
Repeatable result
If you can repeat the experiment multiple times and get the same results
Reproducible result
If someone else can recreate the experiment using different equipment and methods and get the same results
Accurate result
Close to true value
If percentage difference is smaller than percentage uncertainty
Theory is supported by the results
Theory is supported by results
If percentage difference is smaller than percentage uncertainty
If percentage difference is bigger than percentage uncertainty
Theory is not supported by results
Theory is not supported by results
If percentage difference is bigger than percentage uncertainty
